Sulphided ion exchange resins

ABSTRACT

Sulphided ion exchange resins containing primary or secondary amino groups. They may be obtained by passing a non-aqueous liquid, e.g. a hydrocarbon, feedstock containing elemental sulphur or organic, or inorganic, di-or poly-sulphides through a bed of an ion exchange resin containing primary or secondary amino groups, and so unsulphided ion exchange resins containing primary or secondary amine groups may be used to remove such elemental sulphur or sulphur compounds from liquid, e.g. hydrocarbon, feedstocks. The sulphided ion exchange resins may be used to remove elemental mercury or organic mercury compounds from liquid, e.g. hydrocarbon, streams.

This invention relates to sulphided ion exchange resins and theirproduction and use.

Accordingly the invention provides a sulphided ion exchange resincontaining primary or secondary amino groups.

Elemental sulphur or organic, or inorganic, di-or poly-sulphides may bepresent as a contaminant in liquids especially hydrocarbons. One sourceof such contamination is as a result of the transport of hydrocarbonsvia pipelines. In some cases batches of different hydrocarbons arepumped along a pipeline in sequence and as a result “clean” hydrocarbonssuch as gasoline may be contaminated by materials such as hydrogensulphide from the previous use of the pipeline for a “dirty” hydrocarbonsuch as kerosene. Pipeline scale and/or ingress of small amounts of aircan cause the oxidation of contaminants such as hydrogen sulphide toelemental sulphur. Sublimation of elemental sulphur may also result incontamination of gaseous hydrocarbons.

Removal of such elemental sulphur and sulphur compounds is desirable. Wehave found that ion exchange resins containing primary or secondaryamino groups can absorb significant amounts of elemental sulphur.

Accordingly the present invention also provides a method of makingsulphided ion exchange resins containing primary or secondary aminogroups comprising passing a non-aqueous liquid feedstock containingelemental sulphur or organic, or inorganic, di-or poly-sulphides througha bed of an ion exchange resin containing primary or secondary aminogroups.

The process may thus be employed for the removal of such sulphur orsulphur compounds present as contaminants in liquid, e.g. hydrocarbon,feedstocks.

The absorption may be effected at temperatures in the range −10° C. to+100° C. and under sufficient pressure that the feedstock is in theliquid, by which term we include gases in the “dense phase”, state atthe desired absorption temperature. By the term “dense phase” we meanthat the fluid is at a pressure that is above the upper dew point curveand at a temperature above the critical temperature (but generally belowthe temperature of the maxcondentherm point—which is the maximumtemperature of the dew point and bubble point curves).

Amine-containing ion exchange resins as supplied often contain asignificant amount of water. We have found that such water can retardthe absorption of elemental sulphur. Accordingly it is preferred thatthe ion exchange resin is dried, e.g. by extraction with a suitablesolvent such as methanol, before use. The ion exchange resin, of whichAmberlyst A.21 is a typical example, is preferably employed in the formof a fixed bed of shaped units, e.g. spherical granules, preferablyhaving maximum and minimum dimensions in the range 0.5 to 10 mm.

As a result of the aforesaid process, the ion exchange resin becomessulphided. In addition to absorbing the elemental sulphur, the ionexchange resin may catalyse the decomposition of elemental sulphurspecies such as the cyclic S₈ species, forming polysulphides andhydrogen sulphide. Consequently it may be desirable to pass thefeedstock through a bed of a suitable hydrogen sulphide absorbent afterpassage through the bed of the ion exchange resin. Suitable hydrogensulphide absorbents include zinc and copper compounds such as oxides,hydroxides and basic carbonates. A particularly suitable absorbent thatis effective at the temperatures mentioned above comprises agglomeratesof co-precipitated copper, zinc and aluminium compounds and may containa suitable binder, e.g. a calcium aluminate cement.

Liquid feedstocks that may be treated include any non-aqueous liquidsthat are liquid under the operating conditions. Preferred hydrocarbonsinclude natural gas liquids and gasoline.

If desired, the ion exchange resin can be regenerated by periodictreatment with a suitable acid such as hydrochloric acid. However underfavourable conditions, the ion exchange resin may have the capacity toabsorb a sufficient amount of sulphur that it is economic to replace theresin when laden with the absorbed sulphur rather than to provide forregeneration. Alternatively the sulphided ion exchange resin may be usedto adsorb elemental mercury and/or organic mercury compounds asdescribed below.

In addition to, or instead of, sulphur compounds, elemental mercuryand/or organic mercury compounds may be present as a contaminant innon-aqueous fluids, e.g. hydrocarbon, streams, e.g. gas or oil asextracted from the earth. The presence of mercury or organic mercurycompounds is undesirable since elemental mercury can cause severecorrosion problems while organic mercury compounds tend to be toxicand/or readily decomposed to elemental mercury. Removal of suchelemental mercury and organic mercury compounds is desirable. We havefound that sulphided ion exchange resins containing primary or secondaryamino groups, for example as obtained in the aforesaid process, canabsorb significant amounts of mercury.

Accordingly the present invention provides a method for the removal ofmercury and organic mercury compounds from a non-aqueous liquid, e.g.hydrocarbon, feedstock comprising passing the feedstock through a bed ofa sulphided ion exchange resin containing primary or secondary aminogroups.

As for the original sulphiding process, the absorption may be effectedat temperatures in the range −10° C. to +100° C. and under sufficientpressure that the feedstock is in the liquid or “dense phase”, state atthe desired absorption temperature.

In addition to absorbing the elemental mercury, the sulphided ionexchange resin may remove organic mercury compounds by catalysing theirdecomposition with the absorption of the mercury thus formed or by othermeans.

Where the liquid feedstock stream also contains sulphur, the ionexchange resin may be sulphided in situ. However, in order to ensurethat the mercury is absorbed, it is preferred that at least the inletportion of the bed of ion exchange resin is sulphided before a mercurycontaining stream is passed through the bed.

Hydrocarbons that may be treated include any that are liquid under theoperating conditions. Preferred hydrocarbons include natural gas liquidsand gasoline.

The invention is illustrated by the following examples.

EXAMPLE 1

A stirred vessel was charged with 200 ml of toluene in which about 10 mgof sulphur had been dissolved at room temperature. 5 g of an ionexchange resin, Amberlyst A.21 which contains methylamino groups, in theform of spherical granules of diameter about 1.5 mm was added to thevessel and stirring continued. Samples of the solution were taken foranalysis at intervals. As no significant reduction in the sulphurcontent occurred after 165 minutes, a further 5 g of the ion exchangeresin was added and stirring, and intermittent sampling, continued for afurther 3 hours. Stirring was then stopped and the vessel left to standfor 7 days. The sulphur content of the solution is shown in the Table 1.TABLE 1 Total sulphur content Time (mg/l) 0 min 45.5 10 min 46.1 30 min46.1 165 min 44.1 210 min 34.3 300 min 18.2 345 min 8.3 7 days 0

It is seen that the sulphur was only absorbed slowly.

EXAMPLE 2

The procedure of example 1 was repeated without the addition of thesecond 5 g 5 of ion exchange resin and the vessel was left to stand for3 days. The results are shown in Table 2. TABLE 2 Total sulphur contentTime (mg/l) 0 min 44.1 30 min 43.2 60 min 44.0 180 min 40.7 240 min 35.8315 minn 23.0 360 min 14.5 3 days 3.5

EXAMPLE 3

Analysis of the Amberlyst A 21 ion exchange resin as used in Examples 1and 2 revealed that its initial water content was about 50% by weight.In order to reduce the water content, 10 g of the Amberlyst A21 resinwas extracted in a separating funnel with two 50 ml aliquots ofmethanol. The methanol was then drained off and the resin dried in astream of nitrogen. The procedure of Example 2 was then repeated usingthe extracted resin and a solution of 13 mg of sulphur in 200 ml oftoluene. The results are shown in Table 3. TABLE 3 Total sulphur contentTime (min) (mg/l) 0 44.5 30 37.0 90 0.04 220 0

It is seen that the sulphur was rapidly absorbed.

EXAMPLE 4

To assess the capacity of the Amberlyst A 21 ion exchange resin forsulphur, 5 g of the resin was added to a solution of 2527 mg of sulphurin 200 ml of toluene. Samples of the resin were removed at intervals,air dried and then analysed for total sulphur. The results are shown inTable 4. TABLE 4 Time (hours) sulphur content (mg/cm³) 5.5 14 7 19 24 4151 51

1. A method of making a sulphided ion exchange resin containing primaryor secondary amino groups and the concomitant removal of elementalsulphur or organic or inorganic di- or poly-sulphides from a non-aqueousliquid feedstock comprising passing said feedstock containing elementalsulphur or organic or inorganic di- or poly-sulphides through a bed ofan ion exchange resin containing primary or secondary amino groups,thereby forming a sulphided ion exchange resin containing primary orsecondary amino groups.
 2. A method according to claim 1 wherein thenon-aqueous liquid feedstock is passed through a bed of a hydrogensulphide absorbent after passage through the bed of the ion exchangeresin.
 3. A method according to claim 1 wherein water is removed fromthe ion exchange resin before use.
 4. A method according to claim 1wherein the ion exchange resin is in the form of a fixed bed of shapedunits having maximum and minimum dimensions in the range 0.5 to 10 mm.5. A method according to claim 1 wherein the non-aqueous liquidfeedstock is contacted with the ion exchange resin bed at temperaturesin the range −10° C. to +100° C. under sufficient pressure that thefeedstock is in the liquid state.
 6. A method according to claim 1wherein the ion exchange resin is periodically regenerated by treatmentwith an acid.
 7. A method according to claim 1 where the liquid is ahydrocarbon.
 8. A method according to claim 7 wherein the liquid isselected from the group consisting of natural gas liquids and gasoline.9. A method according to claim 1 wherein said non-aqueous liquidfeedstock further comprises mercury or inorganic mercury compounds, andwherein at least the inlet portion of the bed of an exchange resin issulphided before a mercury containing stream is passed through the bed,thereby to remove said mercury or organic mercury compounds from saidnon-aqueous liquid feedstock.
 10. A sulphided ion exchange resincontaining primary or secondary amino groups obtained by a methodaccording to claim
 1. 11. A method for the removal of mercury andorganic mercury compounds from a non-aqueous liquid feedstock comprisingpassing the feedstock through a bed of a sulphided ion exchange resincontaining primary or secondary amino groups according to claim
 1. 12.(canceled)
 13. A method according to claim 11 wherein the liquid is ahydrocarbon.
 14. A method according to claim 13 wherein the liquid isselected from the group consisting of natural gas liquids and gasoline.15. A method according to claim 11 wherein the ion exchange resin is inthe form of a fixed bed of shaped units having maximum and minimumdimensions in the range 0.5 to 10 mm.
 16. A method according to claim 11wherein the non-aqueous liquid feedstock is contacted with the ionexchange resin bed at temperatures in the range −10° C. to +100° C.under sufficient pressure that the feedstock is in the liquid state.